Drive systems of this general type are not new per se. For example, U.S. Pat. No. 2,568,646 shows a drive system wherein the outer bearing ring is formed by a two-row grooved ball bearing and the inner bearing is formed by a journal-bearing bushing mounted in the housing bore of the pump cover. This known system has several disadvantages and drawbacks. For example, it has been found that bearing play is present to a greater or lesser extent in both the inner and outer bearings. Consequently, the pump impeller runs roughly and generates noise. The shaft and drive wheel, therefore, exhibit radial axial vibrations within the individual bearing play. The shaft and drive wheel, therefore, tend to vibrate axially and radially by reason of the bearing play which results in damage and destruction of the components of the drive system such as the sealing lip of the sliding ring on the pump shaft.
By reason of the difference in bearing play between the inner and the outer bearing it is necessary to provide a bolt secured in a manner to allow the drive wheel to shift relative to the shaft of the impeller in these known drive systems. Attaching the bolt loosely in this way, however, is undesirable.